COMMENT

Name: Admin

There are several points to consider while planning to buy one among these OS.
1. What is your budget?
2. Do you need a tech support?
3. Are you inclined to open source codes?

If you are not a tech guy then prefer vista, even better windows xp.
If you are a developer and this is your second PC then you might buy an Ubuntu OS.
Ubuntu has driver issues as it is not developed completely, if you are ready to face this hassles and support open source then please go ahead.